Container of biodegradable heat-resistant hard resin molding

ABSTRACT

A shaped container of biodegradable, heat-resistant and rigid resin having a laminate structure including a glycolic acid polymer layer and another biodegradable resin layer, is formed by shaping under heating so that another biodegradable resin forms an outer and/or inner layer. The container is excellent in biodegradability, stiffness and heat resistance as well as excellent see-through of contents, and is suitable as a temporary preservation container for food, etc.

TECHNICAL FIELD

The present invention relates to a shaped container of a biodegradable,stiff, heat-resistant and rigid resin, suitable as a temporarypreservation container for contents, such as food.

BACKGROUND ART

Polylactic acid and succinic acid-based aliphatic polyesters, etc., havedrawn interest as biodegradable resins harmonizable with environment. Ifthey can be used to form a temporary preservation container for food,the container is expected to be disposed without causing garbage bybiodegradation thereof after the use, and also expected be compostedtogether with contents such as food after expiry of the relishableperiod thereof, thus eliminating an operation, such as separation ofmaterials. However, as these resins are inferior in heat resistance, acontainer made thereof can be softened or deformed when heated forre-warming the food and can sometimes cause overflow of the contents,thus being liable to cause soiling of the surroundings or scald of theuser. Further, a container made of these resins is liable to causeoxidative degradation of the contents such as food, due to gaspenetration therethrough.

On the other hand, polyglycolic acid is known as a crystallinebiodegradable resin having a melting point of 180° C. or higher and ahigh gas-barrier property, but a relatively thick sheet thereof isliable to cause whitening when shaped under heating, so that thesee-through of the resultant shaped container is impaired. Accordingly,though a glycolic acid polymer as represented by polyglycolic acid hasbeen proposed to form a gas-barrier composite film by lamination withanother thermoplastic resin, such as polylactic acid and succinicacid-based aliphatic polyester (Japanese Laid-Open Application (JP-A)10-80990), but the use thereof as a material for a shaped container of arigid resin has not been substantially practiced.

DISCLOSURE OF INVENTION

In view of the above-mentioned circumstances, a principal object of thepresent invention is to provide a shaped container of rigid resin whichis excellent in biodegradability, stiffness and heat resistance and issuitable as a temporary preservation container of contents, such asfood. More specifically, the present invention aims at realizing such ashaped container of rigid resin by a laminate composite shaped containerincluding a glycolic acid polymer as an essential component resin layer.

According to the inventors' study, it has been found that a glycolicacid polymer layer is a resin very suited for providing a shapedcontainer of composite rigid resin as mentioned above excellent inbiodegradability, stiffness and heat resistance, if it is disposedtogether with another biodegradable resin layer in an appropriatepositional relationship.

More specifically, according to the present invention, there is provideda shaped container of biodegradable, heat-resistant and rigid resin,having a laminate structure including a glycolic acid polymer layer andanother biodegradable resin layer, which has been shaped under heatingso that said another biodegradable resin layer forms an outer and/orinner layer.

The reason why the glycolic acid polymer layer is extremely suited forproviding a composite shaped container having the above-mentionedproperties is because it has the following advantageous propertiescompared with other biodegradable resins, such as lactic acid polymersand succinic acid-based aliphatic polyesters. More specifically, (a)glycolic acid polymer is crystalline and particularly itscrystallization speed is remarkably rapid. Moreover, accompanying thecrystallization thereof, it provides a resin layer exhibiting aremarkably larger stiffness compared with other biodegradable resins.This property is of course remarkably preferable for providing a rigidresin container. (b) However, because of its crystallinity, if a singlelayer of glycolic acid polymer is shaped under heating for providing ashaped container by, e.g., deep drawing or blow molding, the shapedcontainer is defectively whitened as described above. As a result of theinventors' further study, however, it has been found that the whiteningof the single layer of glycolic acid polymer is principally caused as aresult of roughening of the surface at which a tension stress isconcentrated, and the whitening can be remarkably alleviated if it islaminated with another biodegradable resin layer thereover and thensubjected to shaping under heating. The whitening due to rougheningduring shaping of the glycolic acid polymer layer surface is causedparticularly remarkably on its outer surface subjected to a largerdegree of deformation, and accordingly a larger degree ofwhitening-prevention effect can be attained if another biodegradableresin layer is disposed on an outer surface than an inner surface of theglycolic acid polymer layer. However, a further betterwhitening-prevention effect can be attained when such anotherbiodegradable resin layer is disposed on both the outer and innersurfaces of the glycolic acid polymer layer. (c) The glycolic acidpolymer layer forming the shaped container in lamination with anotherbiodegradable resin layer is crystallized to increase its stiffnessduring the shaping under heating and optionally performed heat-settingtreatment, thereby providing a rigid resin shaped container suitable fortemporary preservative storage of food. (In contrast thereto, a lacticacid polymer exhibits a very slow crystallization speed, so that thecrystallization thereof hardly proceeds during the heat-settingtreatment.) (d) Further, glycolic acid polymer is caused to have aremarkably increased heat resistance as high as not to cause asubstantial deformability in lamination with another bio-degradableresin layer during 1 minute or longer of heating in a microwave heater.(Incidentally, a succinic acid-based polyester has a very low meltingpoint (of ca. 100° C.) and also a low crystallinity, thus being poor inboth heat resistance and rigidity (or stiffness). (e) Glycolic acidpolymer has a much higher gas-barrier property compared with not onlyother biodegradable resins as a matter of course but also EVOH(ethylene-vinyl alcohol copolymer) which is a conventionally usedrepresentative gas-barrier resin, as high as ca. 3 times or higher(i.e., ca. ⅓ or lower in terms of an oxygen transmission co-efficient)as that of EVOH, so that it can provide, e.g., a bottle shapedtherefrom, exhibiting a remarkably enhanced effect of preserving thecontents in the bottle. (f) Glycolic acid polymer has a biodegradabilitycomparable to or even higher than those of other biodegradable resinssuch as lactic acid polymers and succinic acid-based aliphatic polyesterresins. Accordingly, a shaped container having a laminate structureconsisting essentially of these biodegradable resin layers can bedisposed without causing garbage, by biodegradation thereof after theuse as a temporary preservation container for food, etc., and can alsobe composed together with contents such as food after expiry of therelishable period thereof.

The shaped container of biodegradable, heat-resistant and rigid resinaccording to the present invention has been completed based on theabove-mentioned findings.

EMBODIMENTS OF THE INVENTION

(Glycolic Acid Polymer)

Glycolic acid polymer is a biodegradable (hydrolysable) and crystallinepolyester having a recurring unit represented by a formula (1) below:—(OCH₂CO)—  (1)

It is preferred to use glycolic acid homopolymer (PGA) consisting onlyof the above recurring unit, but another recurring unit can be containedprovided that a structure having a main chain which can be cut bybiodegradation (or hydrolysis) is preferred.

Preferable structures may include ester structures including carboxylicacid esters and carbonic acid esters, and amide structure. Particularly,an aliphatic ester structure is preferred in view of biodegradability.Examples thereof may include the following:—(OCHCH₃CO)—  (2)—(OCH₂CH₂CH₂OCO)—  (3)—(OCH₂CH₂CH₂CH₂CO)—  (4)The proportion of such another recurring unit structure is below 50 wt.%, preferably below 30 wt. %, further preferably below 15 wt. % in orderto retain the effect of increasing stiffness and heat-resistance due tocrystallization.

Further, it is also possible to incorporate another thermoplastic resinin the glycolic acid polymer layer for the purpose of controlling thecrystallizability thereof in a relatively small amount (e.g., up to 20wt. %) within an extent of not adversely affecting the stiffness andheat-resistance.

As for such another thermoplastic resin, it is not impossible to use ageneral-purpose resin, such as polyethylene, polypropylene, polyvinylchloride or polystyrene, but in order to increase the content ofbiodegradable resin, it is preferred to use another biodegradable resin,such as a lactic acid polymer, succinic acid-based aliphatic polyesterwhich is a poly-condensate of succinic acid and ethylene diol or butanediol, polycaprolactone, ω-hydroxyacetic acid polycondensate and Biomax(registered trade mark, available from Du Pont), cellulose or starch.

(Another Biodegradable Resin)

As for a constituent resin of said another biodegradable resin forforming the rigid resin shaped container of the present inventiontogether with the glycolic acid polymer layer it is possible to usebiodegradable resins, such as a lactic acid polymer, succinic acid-basedaliphatic polyester which is a poly-condensate of succinic acid andethylene diol or butane diol, polycaprolactone, ω-hydroxyacetic acidpolyconden sate and Biomax (registered trade mark, available from DuPont), cellulose or starch, raised above as examples of anotherbiodegradable resin which can be incorporated in the glycolic acidpolymer layer. Among these, it is preferred to laminate a layer oflactic acid polymer which has a relatively good heat-resistance. As anexample of such another biodegradable resin, it is also possible to usea regrind (i.e., recovered and re-pulverized product) of a rigid resinshaped container of the present invention. Such a regrind may comprisebiodegradable resins, such as glycolic acid polymer, lactic acid polymerand succinic acid-based polyester, can further contain an adhesive resinin some cases, and can be used within an extent of not remarkablylowering the transparency of the shaped container of the presentinvention.

In the shaped container of the present invention, such anotherbiodegradable resin is disposed as at least an outer layer or an innerlayer, preferably as an outer layer, with respect to the glycolic acidpolymer layer, but may more preferably be disposed as both an outer andan inner layer so as to provide a structure wherein the glycolic acidpolymer layer is sandwiched between a pair of other biodegradable resinlayers which can be not identical to each other but most preferably eachcomprise a lactic acid polymer layer. The resultant shaped container mayhave a layer structure including at least two layers. Examples of such alayer structure may include: another biodegradable resin/glycolic acidpolymer/another biodegradable resin (possibly containing a regrind), andanother biodegradable resin/regrind/glycolic acid polymer/anotherbiodegradable resin (possibly containing a regrind). The above-mentionedanother biodegradable resin layer can have a two-layer structure ofdifferent resins, and in this case, the entire layer structure maycomprise, for example, succinic acid-based polyester/lactic acidpolymer/glycolic acid polymer/lactic acid polymer, which structure maybe provided with easy sealability because the succinic acid-basedpolyester has a relatively low melting point. In any case, an adhesivelayer can be inserted, as desired, between layers.

(Thickness)

In order to be a rigid resin shaped container having a good stiffnessafter an appropriate degree of heat treatment, the shaped container ofthe present invention is required to have a thickness (a total thicknessof the glycolic acid polymer layer and another biodegradable resinlayer) of averagely at least 100 μm, preferably at least 150 mm,particularly preferably 200 μm or larger. Below 100 μm, when thecontainer is caused to receive a relatively heavy food, such as friedfood, daily dishes or cooked rice, the container is liable to be warpedand the handling thereof is liable to be awkward. The upper limit may bedetermined principally in view of economical factors and generally 5000μm or smaller.

Further, in order to ensure a necessary stiffness while retaining thewhitening prevention effect owing to the lamination, it is preferred theglycolic acid polymer layer has a thickness which is 2-98%, morepreferably 5-80% of the total thickness of the glycolic acid polymerlayer and another bio-degradable resin layer.

(Adhesive Layer)

The shaped container of the present invention can be composed of onlythe above-mentioned glycolic acid polymer layer and anotherbiodegradable resin layer, and this is preferred in order to increasethe biodegradability of the entire container. In the case of onceforming a multilayer sheet and then shaping the sheet by secondaryprocessing, such as (deep) drawing or blow forming, etc., however, it ispossible to insert an adhesive resin layer in order to enhance theinter-layer bonding strength. As the adhesive resin, epoxy-modifiedpolyolefin, crosslinked ethylene-vinyl acetate copolymer, etc., maypreferably be used. The biodegradability of these resins is inferior tothe above-mentioned various biodegradable resins, but the load thereofto the environment can be alleviated due to a small amount thereofbecause the adhesive layer is used in a small thickness of, e.g., ca.0.5-30 μm. If an adhesive resin having a better biodegradability isdeveloped, such an adhesive resin may suitably be used in the presentinvention, of course.

(Shaping Under Heating)

The shaped container of the present invention can be directly formed bya melt resin forming method, such as multilayer injection molding, byblow molding (stretch blow molding) of a laminate preform of glycolicacid polymer layer and another biodegradable resin layer formed by sucha melt-resin forming method, by direct blow molding, inflation,melt-vacuum forming, or by vacuum forming or deep drawing of aonce-formed laminate sheet, as a suitably adoptable technique. Accordingto the vacuum forming, the sheet may be pre-heated for 0.5 sec. to 3min., preferably 1 sec. to 2 min., at 60-120° C., and shaping the sheetso as to fit to a mold by placing the mold under vacuum. The shaping bythe melt vacuum forming may be effected by heating at 160-240° C.,preferably 170-230° C.

(Heat Treatment)

Through the above-mentioned shaping under heating, the shaped containeris provided with increased stiffness and heat-resistance, principallyowing to the crystallization of the glycolic acid polymer layer includedtherein, but can be subjected, as desired, to an additionalheat-treatment (heat-setting) for causing further crystallization toincrease the stiffness and heat resistance. The heat-treatment isperformed at a temperature equal to or higher than a heat-resistanttemperature usually required of the shaped container, preferably100-210° C., more preferably 150-200° C.

The heat-treatment time is not particularly restricted but mayordinarily be 1 sec. to 60 min., preferably 2 sec. to 10 min.,particularly preferably 5 sec. to 5 min. Heat-treatment for less than 1sec. may be insufficient in some cases, and a period longer than 60 min.does not provide a substantially different heat-treatment effect butmerely results in a longer processing time.

(Stiffness, Heat Resistance)

Through the above-mentioned shaping under heating and optionalheat-treatment, the shaped container of the present invention isprovided with necessary level of stiffness and heat-resistance.

A desirable level of stiffness of the shaped container may berepresented by a flexural modulus Ef of at least 100 kg/mm²,particularly at least 150 kg/mm² as measured in a state where a load isapplied from the outer resin layer, and also a factor Ef×t of at least 1kg/mm², particularly at least 2 kg/mm, taking the contribution of thethickness t [mm] into consideration. These values can be also measured,e.g., in the case of sheet forming (shaping), by subjecting a sheetbefore the shaping to a quantity of heat provided to the sheet duringthe actual shaping under heating and heat-treatment, then subjecting theheated sheet to the flexure test and applying a correction to themeasured values corresponding to a thickness reduction after theshaping.

A desired level of heat-resistance of a shaped container of the presentinvention may be represented by no visible deformation of the containerafter placing cooked and cooled rice of ca. 180 cm³ in terms of a drystate volume before the cooking and subjecting the rice in the containerto 1 min. of microwave heating at a power of 500 W.

(Whitening)

The shaped container of the present invention is required to exhibitsuch a level of whitening resistance as to allow seeing-through of thecontents after the shaping under heating. More specifically the shapedcontainer of the present invention is required to exhibit a haze(measured with respect to a cut sheet piece cut out from a side wall ofthe shaped container according to JIS K6714) of at most 50%, preferably20. % or below, more preferably 10% or below. If the haze is above 50%,the shaped container is like a frosted glass sheet so that the contentsare difficult to judge by seeing-through. In contrast thereto, a haze of20% or below represents a state of frosted glass sheet not providing adifficulty for determination of the contents, and a haze of 10% or belowrepresents a good see-through of the contents.

(Use)

The thus-obtained rigid resin shaped container of the present inventionis extremely suitably used as a temporary preservation container forfood which should desirably have heat-resistance, bio-degradabilitydesirable for disposal, stiffness desirable for handling of thecontainer and see-through of the contents, and is also suitably used asa container for medical appliances for which similar properties aredesirable, inclusive of heat-resistance for heat-sterilization. Further,in case where the container is shaped into a bottle, the bottle is alsosuitably used as a container for contents, such as a beverage, dislikingdegradation with oxygen. Further, a regrind of the rigid resin shapedcontainer of the present invention may be utilized, because of itsstiffness, for providing chopsticks or tooth picks (though these can bemade of young wood lumbered for decreasing the wood population),disposable forks, small blown containers for seasonings, small pouches(which be provided with an easy sealability if laminated with a succinicacid-based polyester), “baran” (i.e., a green sheet provided with apattern of bamboo leaf), etc., attached to a container for box lunchfrequently available in convenience stores, and it becomes possible tocompose an entire box lunch set of bio-degradable resins. In thisinstance, these adjuncts can be poor in transparency.

Incidentally, the rigid resin shaped container of the present inventionis formed in a shape suitable for accommodating contents, whereas a flatsheet or film having an identical laminate structure can be used as alid member to be combined with a container of the present inventionformed as a bowl or parallelepiped container to form a containeraccommodating food, etc., capable of microwave heating, by principallyutilizing excellent properties, such as gas-barrier property, heatresistance and biodegradability, of the flat sheet or film.

However, such an open bowl or parallel-piped-shaped container of thepresent invention can also be used in such a manner as to form atemporarily packaged product together with an ordinary food wrappingfilm, etc., adapted to microwave heating. Further, such a container mayalso be used as a deep-drawn packaging material for storing a stackedsliced ham utilizing its property of heat-resistance, pinhole-resistanceor label adhesion, etc., as desired properties. If such a container isrequired of sealability with a lid material, it is possible to dispose alayer of succinic acid-based polyester outside or inside thereof.

The shaped container of the present invention can be combined with abiodegradable film provided separately to provide an entirelybiodegradable package. Examples of specific structures thereof mayinclude the following:

1) A shaped container of the present invention together with contents iscovered with a bio-degradable film, and the edges of the film aresuperposed (wrapped) or further sealing the super-posed edges. Thesealing may be performed with opposite edges of one inner surface(palm-to-palm sealing) or edges of inner and outer surfaces (envelopesealing or back seaming). (More details of such packaging embodimentsare shown in, e.g., JP-A 3-162262 and JP-B 2991526.)

2) The shaped container of the present invention is formed as acontainer bottom having a flange portion surfaced with a sealable resin,and after contents being placed therein, a lid member comprising abiodegradable film is sealed onto the flange portion of the containerbottom to form a package. (Details of this embodiment are shown in,e.g., JP-A 4-72135.)

In either of the above-mentioned embodiments 1) and 2), if thebiodegradable film is heat-shrinkable, the package formed in theabove-described manner may be passed through a shrink tunnel to shrinkthe film, thereby providing a beautiful package.

The biodegradable (heat-shrinkable) film may have a layer structure of,e.g., lactic acid polymer/glycolic acid polymer/succinic acid-basedpolyester. An anti-fog agent can be applied on or incorporated in thebiodegradable film. Such a biodegradable film may be used instead of awrapping film (“KUREWRAP”, made by Kureha Chemical Industry Co., Ltd).used in Examples described hereinbelow.

EXAMPLES

Hereinbelow, the present invention will be described more specificallybased on Examples and Comparative Examples.

Example 1

2 g of pellet form polylactic acid (“LACTY”, made by Shimadzu SeisakushoK.K.) were placed on a 15 cm-dia. and 200 μm-thick amorphous sheet ofpoly-glycolic acid (exhibiting a melt viscosity of 2000 Pa·s at 240° C.and a shear rate of 100/s), and melted in a heat press at 240° C. bypreheating for 1 min. and pressing at 5 MPa for 1 min., followedimmediately by cooling in iced water to form a 300 μm-thick transparentlaminate sheet. After being dried, the thus-obtained sheet was shapedinto a 200 μm-thick bowl with an outer layer of the polylactic acid byair-pressure forming. The bowl was supported by a jig so as to retainits shape and, in this state, was heat-treated at 120° C. for 1 min.After the heat treatment, the bowl retained its shape even after the jigwas removed. The bowl was then placed in an oven at 100° C. but causedno change in outer appearance or shape whereby heat-resistance thereofwas confirmed. The bowl exhibited a haze of 10% or below throughout theshaping, heat-treatment and oven-treatment.

Example 2

Cooked and cooled rice was placed in the bowl-shaped product of Example1, and surface-covered with a wrapping film (“KUREWRAP”, made by KurehaChemical Industry Co., Ltd.), and in this state, was heated for 1 min.in a microwave heater. After the heating, the bowl caused no change inouter appearance or strength and could be taken out together with theheated rice while holding the bowl by hands, so that its heat resistancecould be confirmed.

Comparative Example 1

7 g of pellet-form polylactic acid (trade name: “LACTY 9030”, made byShimadzu Seisakusho) was melted in a heat press at 240° C. by preheatingfor 1 min. and pressing at 5 MPa for 1 min., and then immediately cooledin iced water to form a 300 μm-thick single layer sheet. After beingdried, the thus-obtained sheet was heated at 240° C. and shaped into a200 μm-thick bowl by air-pressure forming. The bowl was supported by ajig so as to retain its shape and, in this state, heat-treated at 120°C. for 1 min. As a result, the bowl was softened at 120° C. and resultedin a shape change after the jig was removed.

Comparative Example 2

A bowl of polylactic acid subjected to heat-treatment in the same manneras in Comparative Example 1 was cooled to room temperature while beingsupported by the jig, whereby the bowl shape could be retained. Cookedand cooled rice was placed in the bowl after cooling, surface-coveredwith a wrapping film and then heated for 1 min. in a microwave heater.After the heating, the bowl was deformed, and the heated rice overflowedout of the deformed bowl.

Comparative Example 3

Polyglycolic acid (melt viscosity: 2000 Pa·s at 240° C. and a shear rateof 100/s) was melted in a heat press at 240° C. by preheating for 1 min.and pressing at 5 MPa for 1 min., and then immediately cooled in icedwater to form a 250 μm-thick single-layer sheet. After being dried, thethus-obtained sheet was heated at 240° C. and shaped into a 150 μm-thickbowl by air-pressure forming. The bowl was supported by a jig so as toretain its shape and, in this state, heat-treated at 120° C. for 1 min.The shaped bowl exhibited a haze of 60%.

Example 3

Polyglycolic acid (PGA), polylactic acid (PLA) (trade name: “LACTY9030”, made by Shimadzu Seisakusho) and ethylene-glycidyl methacrylatecopolymer adhesive resin (“BOND FAST EF-E”, made by Sumitomo KagakuKogyo K. K.) were extruded through a 5-layer T-die extruder to form atrans-parent multiplayer sheet having a layer structure of PLA/adhesiveresin/PGA/adhesive resin/PLA (having thicknesses from the left of90/10/100/10/90 μm).

The thus-obtained multilayer sheet was heated at 80° C. for 1 min. andthen shaped into a 200 μm-thick bowl by air-pressure forming. After theshaping, the bowl was supported by a jig so as to retain its shape and,in this state, heat-treated at 150° C. for 1 min. In the bowl-shapedrigid container, cooked and cooled rice was placed and surface-coveredwith a wrapping film, followed by heating for 1 min. in a microwaveheater. After the heating, the bowl caused no change in outer appearanceor strength and could be taken out together with the heated rice withhands, thus confirming its heat resistance. The bowl exhibited a haze of9% after the microwave heating.

Example 4

The 300 μm-thick multilayer sheet obtained in Example 3 was shaped undervacuum at 100° C. for 2 sec. by using a continuous deep drawing machine,whereby a sufficiently transparent 160 μm-thick lunch box-shapedcontainer could be formed. Similar vacuum forming was confirmed to bepossible by heating in a range of 80-110° C. for 2 sec. After theshaping, the container was supported by a jig so as to retain arectangular lunch box shape and heat-treated at 150° C. for 1 min. Inthe lunch box-shaped rigid container after the heat-treatment, cookedand cooled rice was placed and surface-covered with a wrapping film,followed by heating for 1 min. in a microwave heater. After the heating,the lunch box-shaped rigid container caused no change in outerappearance or strength and could be taken out together with the heatedrice with hands, thus confirming its heat resistance. The containerexhibited a haze of 9% after the microwave heating.

Example 5

The 300 μm-thick multilayer sheet obtained in Example 3 was examinedwith respect to melt-vacuum formability. As a result, it was confirmedpossible to prepare a 160 μm-thick lunch box-shaped container by usingan infrared heater set at 200° C. while adjusting the heating time.After the shaping, the container was supported by a jig so as to retainthe rectangular lunch box shape and heat-treated at 150° C. for 1 min.In the lunch box-shaped rigid container after the heat-treatment, cookedand cooled rice was placed and surface-covered with a wrapping film,followed by heating for 1 min. in a microwave heater. After the heating,the lunch box-shaped rigid container caused no change in outerappearance or strength and could be taken out together with the heatedrice with hands, thus confirming its heat resistance. The containerexhibited a haze of 9% after the microwave heating.

INDUSTRIAL APPLICABILITY

As described above, according to the present invention, there isprovided a rigid resin shaped container, which has a laminate structureincluding a glycolic acid polymer layer and another biodegradable resinlayer, is excellent in bio-degradability, stiffness and heat-resistanceas well as excellent see-through of contents, and is thus suitable as atemporary preservation container for food, etc.

1. A shaped container of biodegradable, heat-resistant and rigid resin,having a laminate structure including a glycolic acid polymer layer andanother biodegradable resin layer, which has been shaped under heatingso that said another biodegradable resin layer forms an outer and/orinner layer.
 2. A shaped container according to claim 1, wherein saidanother biodegradable resin layer is disposed at least as the outerlayer outside the glycolic acid polymer layer.
 3. A shaped containeraccording to claim 2, wherein said outer layer of another biodegradableresin comprises a lactic acid polymer.
 4. A shaped container accordingto claim 2, further including said another biodegradable resin layeralso as an inner layer disposed inside the glycolic acid polymer layer.5. A shaped container according to claim 4, wherein said inner layer ofanother biodegradable resin comprises a lactic acid polymer.
 6. A shapedcontainer according to 5 claim 1, further including an adhesive layerbetween the glycolic acid polymer layer and the outer and/or innerbiodegradable resin layer.
 7. A shaped container according to claim 1,wherein the glycolic acid polymer layer and another biodegradable resinlayer have a total thickness of 100-5000 μm, of which the thickness ofthe glycolic acid polymer layer occupies 2-98%.
 8. A shaped containeraccording to claim 1, which has been treated for heat-setting after theshaping under heating.
 9. A shaped container according to claim 1,exhibiting a flexural modulus Ef of at least 100 kg/mm² as measured in astate where a load is applied from the outer resin layer.
 10. A shapedcontainer according to claim 9, exhibiting a flexural modulus Ef (asmeasured in a state where a load is applied to the outer resin layer)and a container thickness t giving a product Ef×t of at least 1 kg/mm.11. A package, comprising a shaped container of biodegradable,heat-resistant and rigid resin according to claim 1 and a biodegradablefilm.
 12. A package according to claim 11, wherein the biodegradablefilm is heat-shrinkable.
 13. A package according to claim 11 wherein thebiodegradable film includes at least one glycolic acid polymer layer.14. A package according to claim 12, wherein the biodegradable film hasa gas-barrier property.